1. Field of the Invention
The present invention relates generally to apparatus used in making a dental model from a dental impression whereby the patient's teeth are accurately replicated in the dental model. In particular, the present invention relates to novel trays used in casting the dental models and articulation systems used in association with the trays and the models which are cast in the trays.
2. State of the Art
In order to fabricate a dental prosthetic, such as a crown, inlay, bridge, etc., a negative impression of a patient's teeth is taken using an impression material, and a reproduction of the impression is made as a model in the dental laboratory. The reproduction is a solid, positive model or replication of the gums and at least several adjacent teeth in the mouth of the patient. It is necessary to support the replication or dental model on an articulation device to determine proper size, fit and movement of the restorative prosthetic relative to the other teeth of the patient.
The process of forming dental models is widely known and is described in U.S. Pat. No. 5,207,574 and will not be repeated here. Generally, the reproduction of the patient's teeth corresponding to the upper and lower teeth are formed in separate casting steps. The models of the respective upper and lower teeth are then affixed to an articulation device during the preparation of a restorative prosthetic.
Tray and articulation systems to which the present invention is closely related are shown in U.S. Pat. Nos. 5,846,076 and 5,913,681. In U.S. Pat. No. 5,846,076 a tray is shown having a bottom wall and side walls that extend upwardly from the perimeter of the bottom wall to form an open-topped cavity into which dental casting material is poured. The tray is made of elastomeric material so that the tray can be easily removed from the cast model that is formed in the tray. The tray after being stripped from the cast model is then discarded.
In U.S. Pat. No. 5,913,681 a tray is provided that includes a base wall and upwardly extending side walls at the perimeter of the base wall similar to that of U.S. Pat. No. 5,846,076. However, the tray of U.S. Pat. No. 5,913,681 is formed as a single piece from a non-elastomeric, rigid material, and the cast model must be excised with some difficulty from the tray.